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Polydimethyl siloxane/MIL-101 Composites for Enhanced Toluene Adsorption in the Presence of Humidity

preprint
submitted on 24.03.2021, 15:47 and posted on 26.03.2021, 05:33 by Luqman Hakim Mohd Azmi, Pavani Cherukupally, Elwin Hunter-Sellars, Bradley P. Ladewig, Daryl R. Williams
ABSTRACT

Competition between atmospheric moisture and volatile organic compounds (VOCs) for an adsorbent’s sites can significantly impact its VOC removal efficiency. The development of moisture-tolerant adsorbents is essential to address this issue. A vapor phase deposition process using polydimethylsiloxane (PDMS) has created a hydrophobic form of the highly porous, normally hydrophilic, MOF MIL-101. After optimizing the PDMS vapor deposition time and molecular weights, hydrophobicity index calculations verified the improved hydrophobicity of the coated MOF (MIL-PDMS-Sigma-0.25) over its pristine form. The surface area, pore volume as well as single component vapor adsorption of water and toluene capacities were also preserved, resulting to similar performance to MIL-101. Toluene-water vapor co-adsorption experiments were conducted at 40% RH using two toluene concentrations: 0.5% P/P0 and 10% P/P0, mimicking environmental VOC and industrial concentrations, respectively. At 0.5% P/P0, MIL-PDMS-Sigma-0.25 exhibited 60% higher adsorption capacity and twice the rate of toluene capture relative to pristine MIL-101, as well as a 3-fold higher toluene uptake relative to a commercial activated carbon. Preliminary adsorbent regeneration experiments confirm the stability and performance of MIL-PDMS-Sigma-0.25. Using a simple vapor phase modification, this new MOF-composite material offers superior competitive toluene vapor uptake in humidified real-world conditions at VOC concentrations.

Funding

Yayasan Khazanah for PhD sponsorship

EPSRC Centre for Doctoral Training in the Advanced Characterisation of Materials

Engineering and Physical Sciences Research Council

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Research England Global Challenges Research Fund

History

Email Address of Submitting Author

bradley.ladewig@kit.edu

Institution

Karlsruhe Institute of Technology

Country

Germany

ORCID For Submitting Author

0000-0002-2135-1913

Declaration of Conflict of Interest

There are no conflicts of interest.

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